Process for preparing macroreticular resins, copolymers and products of said process

A process for preparing ion exchange resin beads of high specific surface and reduced apparent density of at least about 0.02 density units less than that of gel-type copolymer beads of the same composition made in the absence of a precipitant, which comprises suspension copolymerizing in an aqueous medium (1) a polyvinylidene monomer containing a plurality of ethylenically unsaturated groups in non-conjugated relationship and (2) a monovinyl aromatic hydrocarbon monomer in a liquid precipitant which (a) has low solubility in the aqueous medium, (b) is a solvent for the monomer mixture and (c) does not swell the copolymer resulting from said copolymerization, said liquid precipitant and said polyvinylidene monomer being present in an amount exceeding the critical concentration of each needed for phase separation of the copolymer from the monomer phase as the copolymer is formed, and proportional to the reduction in apparent density desired, as compared to gel copolymer beads of the same composition, recovering the copolymer beads so formed and reacting the same to attach an ion exchange functional group to the copolymer beads.